Why are there two different and disconnected ways to Sync Music Libraries to/through iCloud?

What's the difference between the Mac Music app Sync Library checkbox in "Music Settings/General" VS the "Music" switch to enable/disable Syncing in "System Settings/Apple Account/iCloud/Drive/Apps Syncing to iCloud Drive"? They must do something different. Enabling one doesn't affect the other.

Same kinda' thing in Photos, too.